Yoga (/'jo?g?/; Sanskrit, Listen) is a physical, mental, and spiritual practice or discipline which originated in India. There is a broad variety of schools, practices and goals in Hinduism, Buddhism (particularly Vajrayana Buddhism) and Jainism. The best-known are Hatha yoga and Raja yoga. The origins of yoga have been speculated to date back to pre-Vedic Indian traditions, but most likely developed around the sixth and fifth centuries BCE, in ancient India's ascetic and srama?a movements.[note 1] The chronology of earliest texts describing yoga-practices is unclear, varyingly credited to Hindu Upanishads and Buddhist Pali Canon, probably of third century BCE or later. The Yoga Sutras of Patanjali date from the first half of the 1st millennium CE, but only gained prominence in the West in the 20th century. Hatha yoga texts emerged around the 11th century with origins in tantra. Yoga gurus from India later introduced yoga to the west, following the success of Swami Vivekananda in the late 19th and early 20th century. In the 1980s, yoga became popular as a system of physical exercise across the Western world. Yoga in Indian traditions, however, is more than physical exercise, it has a meditative and spiritual core. One of the six major orthodox schools of Hinduism is also called Yoga, which has its own epistemology and metaphysics, and is closely related to Hindu Samkhya philosophy. Many studies have tried to determine the effectiveness of yoga as a complementary intervention for cancer, schizophrenia, asthma, and heart disease. The results of these studies have been mixed and inconclusive, with cancer studies suggesting none to unclear effectiveness, and others suggesting yoga may reduce risk factors and aid in a patient's psychological healing process.
The origins of yoga are a matter of debate. There is no consensus on its chronology or specific origin other than that yoga developed in ancient India. Suggested origins are the Indus Valley Civilization (3300-1900 BCE) and pre-Vedic Northeast India, the Vedic period (1500-500 BCE), and the srama?a movement. According to Gavin Flood, continuities may exist between those various traditions: [T]his dichotomization is too simplistic, for continuities can undoubtedly be found between renunciation and vedic Brahmanism, while elements from non-Brahmanical, Sramana traditions also played an important part in the formation of the renunciate ideal.[note 5] Pre-philosophical speculations of yoga begin to emerge in the texts of c. 500–200 BCE. Between 200 BCE–500 CE philosophical schools of Hinduism, Buddhism and Jainism were taking form and a coherent philosophical system of yoga began to emerge. The Middle Ages saw the development of many satellite traditions of yoga. Yoga came to the attention of an educated western public in the mid 19th century along with other topics of Indian philosophy.